Austriamicrosystems Delivers Tiny 700-mA LED Driver

Measuring 2 mm x 1.5 mm and less than 600 µm in height, the AS3685 700-mA charge pump-based flash LED driver consumes just 14 mm2 of board space, including four external components. Groomed for camera-flash applications in mobile phones, the device employs a smart charge pump architecture that avoids large spikes at the battery terminals. To avoid excess current draw if the phone’s power amplifier becomes active while a picture is being taken, it reduces flash current to a significantly lower level within less than 1 µs. Safety features include a built-in flash LED time-out function that guarantees flash shutdown via a built-in, factory-programmable timer (typically 800 ms). The chip comes with a multi-mode, 2-pin interface incorporating off, indicator, flashlight, and flash operating modes. The AS3685B variation features a single-wire interface allowing flash current to be set to one of 18 steps depending on actual operating and environmental conditions. The AS3685 is available now in WL-CSP3x4 packaging. AUSTRIAMICROSYSTEMS USA INC., Raleigh, NC. (919) 676-5292.